21001352550 has 48 divisors (see below), whose sum is σ = 52096470672. Its totient is φ = 5598950400.

The previous prime is 21001352507. The next prime is 21001352569. The reversal of 21001352550 is 5525310012.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21001352550.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 668802 + ... + 699498.

It is an arithmetic number, because the mean of its divisors is an integer number (1085343139).

Almost surely, 2^21001352550 is an apocalyptic number.

21001352550 is an abundant number, since it is smaller than the sum of its proper divisors (31095118122).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21001352550 is a wasteful number, since it uses less digits than its factorization.

21001352550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35273 (or 35268 counting only the distinct ones).

The product of its (nonzero) digits is 1500, while the sum is 24.

Adding to 21001352550 its reverse (5525310012), we get a palindrome (26526662562).

The spelling of 21001352550 in words is "twenty-one billion, one million, three hundred fifty-two thousand, five hundred fifty".